Field
Aspects of the present disclosure relate to using a conical-shaped rotor inside a conical-shaped housing to perform Taylor vorticity-enhanced filtration of gray water.
Description of the Related Art
One of the challenges in any type of filtration process, including filtration of gray water, is filter clogging, scientifically described as “concentration polarization.” As a result of the selective permeability properties of the filtration membrane, the filtered material that cannot pass through the membrane becomes concentrated on the surface of the membrane. This phenomenon is illustrated in the case of a “dead-end” filter, such as a coffee filter. During the course of the filtration process, the filtered material (coffee grounds) building up on the filter creates flow resistance to the filtrate, the fluid (coffee), which can pass through the filter. Consequently, filtrate flux is reduced and filtration performance diminishes.
Various solutions to the problem of concentration polarization have been suggested. These include: increasing the fluid velocity and/or pressure (Merin et al., (1980) J. Food Proc. Pres. 4(3):183-198); creating turbulence in the feed channels (Blatt et al., Membrane Science and Technology, Plenum Press, New York, 1970, pp. 47-97); pulsing the feed flow over the filter (Kennedy et al., (1974) Chem. Eng. Sci. 29:1927-1931); designing flow paths to create tangential flow and/or Dean vortices (Chung et al., (1993) J. Memb. Sci. 81:151-162); and using rotating filtration to create Taylor vortices (see e.g., Lee and Lueptow (2001) J. Memb. Sci. 192:129-143 and U.S. Pat. Nos. 5,194,145, 4,675,106, 4,753,729, 4,816,151, 5,034,135, 4,740,331, 4,670,176, and 5,738,792), all of which are incorporated herein in their entirety by reference thereto).
One application of the Taylor vorticity-enhanced filtration technology (herein referred to as “T-V technology”) is in the separation of human blood into cell free plasma and concentrated blood cells. The concentrated blood cells are returned to the blood donor. The cell free plasma is the commercially desired product. In some applications, the T-V technology device may operate for about 30 minutes and may then be discarded. Due to its relatively short duration of use, costs that come with the needs of longevity are avoided, and the device can be made at minimum expense. The relatively high worth of the harvested human blood cell free plasma helps to justify the cost of the single use device.
In some T-V technology used for blood separation, the filter media is on a rotor, and because of this, a rotary fluid transport seal is used. This rotary fluid transport seal allows extraction of the filtered plasma, which is rotating with the rotor, to transit to the stationary case. An inexpensive rotary fluid transport seal works well in the whole blood separation application because it only needs to operate for 30 minutes or so. However, having a rotary seal survive for years of service may be considerably more demanding and expensive.